/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.ddmuilib.logcat;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
/**
* Container for a list of log messages. The list of messages are
* maintained in a circular buffer (FIFO).
*/
public final class LogCatMessageList {
/** Preference key for size of the FIFO. */
public static final String MAX_MESSAGES_PREFKEY =
"logcat.messagelist.max.size";
/** Default value for max # of messages. */
public static final int MAX_MESSAGES_DEFAULT = 5000;
private int mFifoSize;
private BlockingQueue<LogCatMessage> mQ;
/**
* Construct an empty message list.
* @param maxMessages capacity of the circular buffer
*/
public LogCatMessageList(int maxMessages) {
mFifoSize = maxMessages;
mQ = new ArrayBlockingQueue<LogCatMessage>(mFifoSize);
}
/**
* Resize the message list.
* @param n new size for the list
*/
public synchronized void resize(int n) {
mFifoSize = n;
if (mFifoSize > mQ.size()) {
/* if resizing to a bigger fifo, we can copy over all elements from the current mQ */
mQ = new ArrayBlockingQueue<LogCatMessage>(mFifoSize, true, mQ);
} else {
/* for a smaller fifo, copy over the last n entries */
LogCatMessage[] curMessages = mQ.toArray(new LogCatMessage[mQ.size()]);
mQ = new ArrayBlockingQueue<LogCatMessage>(mFifoSize);
for (int i = curMessages.length - mFifoSize; i < curMessages.length; i++) {
mQ.offer(curMessages[i]);
}
}
}
/**
* Append a message to the list. If the list is full, the first
* message will be popped off of it.
* @param m log to be inserted
*/
public synchronized void appendMessages(final List<LogCatMessage> messages) {
ensureSpace(messages.size());
for (LogCatMessage m: messages) {
mQ.offer(m);
}
}
/**
* Ensure that there is sufficient space for given number of messages.
* @return list of messages that were deleted to create additional space.
*/
public synchronized List<LogCatMessage> ensureSpace(int messageCount) {
List<LogCatMessage> l = new ArrayList<LogCatMessage>(messageCount);
while (mQ.remainingCapacity() < messageCount) {
l.add(mQ.poll());
}
return l;
}
/**
* Returns the number of additional elements that this queue can
* ideally (in the absence of memory or resource constraints)
* accept without blocking.
* @return the remaining capacity
*/
public synchronized int remainingCapacity() {
return mQ.remainingCapacity();
}
/** Clear all messages in the list. */
public synchronized void clear() {
mQ.clear();
}
/** Obtain a copy of the message list. */
public synchronized List<LogCatMessage> getAllMessages() {
return new ArrayList<LogCatMessage>(mQ);
}
}